Electric switch control apparatus, such as switchboard boxes or control pushbutton stations of electric plants for handling or transportation, generally include a box-like body, which houses one or more electric switch devices designed to be connected to the electric terminals of respective electric circuits.
Particularly, switch devices include one or more switch contact units, of single- or double-contact type, each having an enclosure that contains pairs of fixed and movable contacts associated with an actuating cursor.
The latter is designed to interact with an actuator, such as a pushbutton or a selector, which is anchored to the box-like body, generally to a movable or removable part thereof.
For example, in the case of switchboards, actuators are anchored to a closing panel of the box-like body, whereas in the case of control pushbutton stations, the cover of the box is used for anchoring purposes.
As a rule, contact units are coupled to the corresponding actuators by snap fit means, allowing anchorage of one or more contact units, with the actuator portion extending from the panel into the box-like body.
Nevertheless, prior art solutions do not ensure stable anchorage of the contact units with their respective actuators, particularly if control apparatus are subjected to shocks caused by accidental falls or impacts by users.
In an attempt to at least partially obviate these drawbacks, switch control apparatus, and particularly control pushbutton stations have been proposed, which integrate additional anchor means acting upon the contact units to prevent or limit movements thereof in the box-like body.
For example, a control pushbutton station is known, which has a cage for absorbing any direct or indirect axial shock upon the contact units, by supporting such units at a bottom wall.
While a higher stability is imparted to each contact unit in this solution, only axially-directed forces may be counteracted, and no resistance is afforded to lateral stresses, whereby the risk of separation is not totally prevented.
Furthermore, as the cage is positioned, it may block the passages that are formed in the enclosure on the contact unit to allow access to the terminals of the fixed contacts and introduction of the terminals of the electric circuits, thereby adding complexity to the installation process.
A further serious drawback is that this particular type of anchor means is not adapted to pushbutton stations that allow coupling of various numbers of contact units to a single contact, which makes the entire apparatus poorly flexible.
A further prior art pushbutton station uses a protective plate located at the bottom walls of the contact units and anchored to the cover of the push-button station. The plate has such a size as to cover all the contact units at the same time, thereby preventing any separation thereof in the axial direction.
Nevertheless, once again protection is restricted, as the plate does not ensure any lateral support. Furthermore, like in the previous case, the plate covers the entire passages formed in the enclosure, and cannot accommodate any change in the number, configuration and type of contact units that can be received in the pushbutton station at the same time.